1. The Field of the Invention
The present disclosure relates generally to orthopedic implants and devices, and more particularly, but not necessarily entirely, to an orthopedic implant, augment, and connector used in a revision surgery to rebuild a resected portion of bone that has been damaged, diseased, or otherwise diminished.
2. Description of Related Art
The knee joint is comprised essentially of four bones, the fibula, the tibia, the femur, and the patella or knee cap. The two major bones, namely the proximal portion of the tibia and the distal portion of the femur, articulate with one another forming the main articulation surface of the knee joint.
It is accepted practice in the orthopedic industry to replace a damaged or diseased knee joint with an artificial implant that acts a replacement knee joint. Following an original knee replacement surgery, there is potential for the tibia and femur to each experience damage or disease for various reasons, resulting in one or more of the prosthetic components that form the artificial knee implant to loosen from the patient's bone thereby causing that component to fail. When one or more of the prosthetic components fails, it may become necessary for an orthopedic surgeon to correct the deficiency in the artificial knee joint during a follow-up revision surgery.
As part of the revision surgery, a surgeon may have to remove the damaged or diseased bone, and may even need to replace one or more of the prosthetic components of the knee joint with a new prosthetic component or components. The reason for the replacement is commonly because either the individual components of the implant, or the bones themselves, have been damaged causing the failure. In either scenario, the damage to the components or bones will likely require the surgeon to resect additional bone from either the tibia or femur, or both, to remove the affected prosthetic components, and to replace those prosthetic components.
It will be appreciated that there is typically less bone for the surgeon to work with during the revision surgery as compared to the original surgery, since some amount of bone has been previously resected during the original surgery. Additional resection of the bone during the revision surgery further limits the amount of bone to which the new prosthetic components of the implant may be attached. At times, the surgeon may not have enough bone to adequately maintain an original joint line, which is formed between the tibial and femoral prosthetic components. It has become accepted practice in the orthopedic industry to provide augments or wedges to increase the height of the prosthetic components in order to help rebuild the resected portion of the bone, to thereby stabilize the revision components and maintain the joint line. It will be appreciated that these augments or wedges may be directly attached to the new femoral or tibial components. The augments not only function to increase the height of the implant to rebuild the joint line, where the original tibial and femoral prosthetic components articulated with one another in the original prosthetic knee joint, but also function to provide the necessary support for the new components of the revision implant. With the aid of the augments, the new revision components may be properly secured to the limited amount of bone present in the knee joint.
Attempts have been made in the art to provide an efficient connection between the augments and new prosthetic components. For example, U.S. Pat. No. 5,370,693 (granted Dec. 6, 1994 to Kelman et al.) discloses an implant having an augment configured to be attached to a surface of the implant by bone cement to compensate for bone loss. The augment is formed to include an aperture defined by an inner wall. Kelman et al. also discloses a peg that is configured to engage the inner wall of the aperture in the augment thereby retaining the augment in a spaced apart relation relative to the implant to permit the implant to be installed onto the bone before the bone cement cures. This device is characterized by several disadvantages, including the need to use bone cement to attach the augment to the implant, which may permit the augment to loosen over time from the implant.
There are several other augment or wedge devices known in the art, such as that disclosed in U.S. Pat. No. 5,458,637 (granted Oct. 17, 1995 to Hayes). This patent reference discloses an augmentation block that includes an attachment mechanism that uses a button and a key hole shaped opening in a tibial tray component to attach the augmentation block to the tibial tray component. This device is disadvantageous because the button locks to the key hole through a top surface of the implant, which key hole is formed completely through the tibial tray. Such a hole formed through the tibial tray may disadvantageously introduce unwanted wear debris pathways into the implant.
It is noteworthy that none of the prior art known to applicant provides a locking mechanism for securing an augment member to a tibial tray component or a femoral component that locks via an interference snap-fit, without fastening the augment member to a through hole extending through a top surface of the tibial tray component or femoral component. There is a long felt, but unmet, need for an augment member that may be securely locked to the implant without introducing unwanted wear debris pathways. Applicant has thus conceived of a locking feature that is simple in design and manufacture, and that may limit, or even eliminate, wear debris pathways.
The prior art is thus characterized by several disadvantages that are addressed by the present disclosure. The present disclosure minimizes, and in some aspects eliminates, the above-mentioned failures, and other problems, by utilizing the methods and structural features described herein.
The features and advantages of the disclosure will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by the practice of the disclosure without undue experimentation. The features and advantages of the disclosure may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.